Grinding machine for ring-like workpieces



A B-5E 25, 16? F. P. HEALY 3,315,416

GRINDING MACHINE FOR RING-LIKE WORKPIECES Filed Nov. 27, 1964 3Sheets-Sheet 1 I N VEN TOR. @A/va/J F A4540 13 Y April 25, W57 F. P.HEALY 3,315,416

GRINDING MACHINE FOR RING-LIKE WORKPIECES Filed Nov. 27, 1964 5Sheets-Sheet :5

April 25, 1967 F. P. HEALY GRINDING MACHINE FOR RING-LIKE WORKPIECES 3Sheets-Sheet Filed Nov. 27, 1964 AQQAMVQJJQJQZ United States Patent3,315,416 GRINDING MACHINE FOR RING-LIKE WORKPIECES Francis P. Healy,Springfield, Mass., assignor to Universal American Corporation,Springfield, Mass., a corporation of Delaware Filed Nov. 27, 1964, Ser.No. 414,197 11 Claims. (Cl. 51105) This invention relates to a machinefor precision grinding of the peripheral surface of ring-like workpiecessuch as the inner race ring of anti-friction ball bearing units whereinan annular groove must be ground as nearly perfectly circular aspossible on a center which will fall on the axis of a shaft on which thebearing unit is ultimately to be mounted.

It is the general object of the invention to provide a machine for theaforementioned purpose and which will perform the grinding operationwith a centerless grinding technique and wherein the workpiece is sosupported and rotated while being ground that the accuracy and precisionwith which the grinding is performed will not depend upon the bearing ormounting precision of the workhead spindle which effects rotation of theworkpiece.

It is a more specific object of the invention to provide an arbor forsupporting ring-like workpieces so that their peripheral surfaces can beground as nearly perfectly cylindrical as possible and wherein theaccuracy of the grinding operation for this purpose depends only uponthe accuracy with which thearbor is constructed and not upon theprecision of operation of other machine elements.

The drawings show a preferred embodiment of the invention and suchembodiment will be described, but it will be understood that variouschanges may be made from the construction disclosed, and that thedrawing and description are not to be construed as defining or limitingthe scope of the invention, the claims forming a part of thisspecification being relied upon for that purpose.

Of the drawings:

FIG. 1 is a front elevational view of a portion of the grinding wheeland the workhead which are operatively associated in the machine of thepresnt invention;

FIG. 2 is a perspective view of the front end portion of the machineworkhead and showing a longitudinal section taken along the axis of theworkhead spindle;

FIG. 3A is a longitudinal vertical sectional view taken through theworkhead on the spindle axis, the view being on an enlarged scale andshowing only the rear end portion of the spindle; and

FIG. 3B is like FIG. 3A but shows the front end portion of the workheadspindle and theattaehments there to.

A grinding machine provided in accordance with the present inventionincludes as essential elements a driven rotatable grinding wheel and aworkhead which is indicated generally by the reference numeral 12. Thegrinding wheel 10 is rotated on a horizontal fore-and-aft axis and isdriven by conventional means not sown. The said grinding wheel and theworkhead 12 are movable relative to each other and, preferably, for thispurpose the workhead 12 can be mounted in place of a regulating wheelassembly in a centerless grinder such as shown in Healy et al. US.Patent No. 3,080,686. When so mounted, the workhead 12 can bereciprocated laterally toward and away from the periphery or operatingsurface of the grinding wheel 10. The means for so reciprocating theworkhead are conventional and are not shown since they form no part ofthe present invention. However, it is to be understood that the workhead12 is moved laterally toward the grinding wheel to engage a workpiecetherewith for grinding and it is then moved laterally away from thegrinding wheel for removal of the ground workpiece and replacement by aworkpiece to be ground.

FIGS. 2, 3A and 3B illustrate the details of the workhead necessary foran understanding of the present invention. Included in this workhead isan elongated hollow workhead spindle 14 which is rotated on a horizontalaxis substantially parallel to the axis of the grinding wheel 10. Thesaid spindle 14 is supported for rotation in a spindle housing 16 onrear anti-friction ball bearing units 18, 18 and similar front units 20,20.

As seen in FIG. 3A, the rear end of the hollow spindle 14 projectsoutwardly from its housing 16, and a pulley 22 is secured thereto forrotating the said spindle, the said pulley being connected to a suitabledrive motor by belting (not shown).

An elongated hollow adapter or mount 24 is also coaxially secured to theextending rear end of the work head spindle 14, this mount beingprovided for a collector ring 26 having brushes 28, 28. The saidcollector ring and brushes are provided to receive electrical power froma source (not shown) so that electrical conducting wires can be extendedfrom said ring through the bore of its mount 24 and forwardly throughthe bore of the spindle 14 to energize an electromagnetic chuck 30 (FIG.3B) which is secured to a flange 32 on the front end of the spindle 14and which is also hollow or annular and coaxial with the said spindle.An actuating rod 34 extends rearwardly from the bore of the magneticchuck 30 through the bore of the spindle 14 and the collector ring mount24. This actuator rod is used in a control function which will bedescribed hereinafter, and it is supported adjacent its front end in abushing 36 at the front end of the spindle 14 and it is also supportedadjacent its rear end in a bushing 38 located in the bore of an antifriction ball bearing unit 40 in the fixed frame structure F which islocated rearwardly of the workhead spindle housing 16. The said frontbushing 36 is provided with.

suitable peripheral flats 42, 42 which accommodate the wires extendingto the magnetic chuck 30 from the collector ring 26.

The projecting rear end portion of the actuating rod 34 is engaged by aclevis-like element 44 on the end of a piston rod 46 which isreciprocated axially in a fluid motor cylinder 48. The fluid motorcylinder 48 is fixedly mounted in another portion of the frame Frearwardly of the workhead spindle housing 16, and the clevis-likeconnection it has with the rear end of the actuating rod 34 permits thesaid rod to rotate with the spindle 14, but this connection permits thefluid motor to move the said rod rearwardly and forwardly in the controlfunction to be described.

An arbor 50, (FIGS. 2 and 3B) is an important element in the presentinvention. This arbor includes a rearwardly projecting cylindrical shank52 and a forwardly projecting cylindrical shank or hub 54 which iscoaxial with the shank 52, and it also includes a coaxial cylindricalflange 56 interposed between the said shanks. The said arbor is locatedon the front end of the magnetic chuck 30 with its rearwardly projectingshank 52 extending into the bore of the said chuck in loosely fittingrelationship, which is greatly exaggerated in FIG. SE, to permit limitedradial movement of the said arbor 50 relative to the said chuck 30. Whenengaged with the chuck, the rear face of the cylindrical flange 56engages the front face of the chuck 30 for radial sliding movementrelative thereto. A bronze bushing 58 is located in the bore of thechuck 30 to divert the flux path of the said magnetic chuck from passagethrough the rearwardly extending shank 52 of the magnetic arbor 50. Thiscauses the flux path to be concentrated in the magnetic flange 56 of thearbor in a circular path which flows through the chuck and its boreforwardly in the arbor to the flange and then radially outwardly backinto the chuck.

The other or forwardly projecting shank 54 of the arbor 50 extends intothe plane of the grinding wheel 10 andis adjacent to the periphery ofthe said grinding wheel. A cylindrical sleeve 6% is mounted on theforwardly projecting shank 54 in snug relationship thereto as by screws'63, 63 projecting through a radial flange on the rear end of saidsleeve and into the cylindrical flange 56' of the arbor. This sleeve isused for the mounting of a workpiece W such as the inner race of ananti-friction bearing unit, the said race or ring being thrust over thesleeve on the bore of the ring.

In keeping with the present invention, the sleeve 60 is to be radiallyexpanded to engage the bore of the workpiece W in a non-slip fit wherebythe said workpiece will be firmly held and can be rotated in engagementwith the grinding wheel 10. The sleeve can also be relaxed to permitremoval and replacement of the said workpiece with a similar piece. Toaccomplish this, the arbor t defines a self-contained hydraulic fluidsystem. More specifically, the said arbor is provided with a rearwardlyextending axial bore 62, a forwardly extending axial bore 64 in thefront shank 54, and a plurality of radially extending bores 66, 66 inthe said forwardly extending shank. A plug 68 is located in therearwardly extending passage 62 and is biased to a closed or normalposition therein by a spring 70 which is seated on a seat 72 threadedinto the rear end portion of the rearwardly projecting arbor shank 52.The spring 70 provides sufficient force when adjusted by the seat 72 tomaintain the plug 68 in the position shown in FIGS. 2 and 3B and therebyto establish suflicient hydraulic pressure to expand the sleevefitl'into the non-slip engagement with the bore of a workpiece W. Thesaid required hydraulic pressure within the system is created orestablished by an adjustable plug 74 which is threaded into the end ofthe forwardly extending passage 64. By threading the plug 74 inwardly,the pressure on the hydraulic fluid within the system is increased tothe desired level. Thus, normally, pressure is maintained in the arborto expand the sleeve 60 into the non-slip working engagement with theworkpiece W.

This pressure is reduced so that the sleeve 60 will relax and permitremoval and replacement of the workpiece W by rearward movement of thepreviously mentioned plug 68. The plug 68 is moved rearwardly to reducethe hydraulic pressure and against the bias of the spring 70 by thefluid motor 46, 48 which engages and moves the actuating rod 34rearwardly. The said actuating rod is provided with a elevis-likeelement 76 at its front end which engages the rear end of the plug 68.When the fluid motor is operated to move the actuating rod 34rearwardly, it in turn retracts or moves the plug 68 rearwardly toincrease the passage volume in the arbor 50 and thereby to reduce thehydraulic pressure therein. This, of course, is done only when theworkhead 12 has been shifted laterally away from the grinding wheel to aposition wherein workpieces can conveniently be interchanged on theforwardly projecting shank of the arbor 50. After a ground workpiece hasbeen removed and replaced by an unground workpiece, the fluid motorpressure is released which releases the plug 68 so that it will resumeits normal position under the force of the spring 70.

7 While the workhead spindle 14 and magnetic chuck 30 engage the arbor50 to rotate it and a workpiece W thereon for grinding, they do notlocate the axis of rotation of the said arbor and workpiece. This isdone by a pair of shoes 80, 80 (FIGS. 1 and 2) which are suitablymounted on a bracket 82 carried by the workhead 12. The shoes 80, 80 arelocated in circumaxially spaced apart relationship to engage thecylindrical periphery of the arbor flange 56. These shoes when engagingthe said arbor flange support the said arbor and its associatedworkpiece for rotation on an axis which is independent of the workheadspindle and magnetic chuck and their common axis. Preferably, the shoes80, '80 are respectively located on opposite sides of a vertical planewhich includes the axis of the workhead spindle and, preferably, thesaid shoes are so located as to shift the independent axis of rotationlaterally away from the spindle axis toward the grinding wheel anddownwardly from the said spindle axis.

With the arrangement described, the annular ball groove in theperipheral surface of the workpiece W can be ground nearly perfectlycircular. That is, the grinding is accomplished, due to the fact thatthe arbor 50 can float relative to the spindle 14 and chuck 30, withoutdepending for accuracy upon the alignment of the workhead spindle andits ability to rotate without an out of round path. Preferably, afterthe sleeve 60 has been mounted on the forwardly projecting shank 54 ofthe arbor 50, its periphery is ground or otherwise machinedconcentrically or coaxially with the cylindrical periphery of the arborflange 56 which is engaged by the shoes 80, 80. Thus, error is minimizedin grinding the workpiece by supporting the arbor on its flange.

In effect, what is accomplished by this means and technique of grindingis that the peripheral surface of the workpiece is ground on the axis ofthe arbor and more particularly on the common axis of the arbor flange56 and the sleeve 60, and this axis is duplicated or very substantiallyduplicated by the axis of the shaft on which the workpiece is ultimatelyinstalled. Thus, we have an inner bearing race or ring which isaccurately ground with reference to the axis of the shaft upon which itis applied.

It is to be understood that the bore of the workpiece W may be out ofround, but since this bore is snugly or press fit in the non-slipengagement on the arbor when it is ground, the out of round error isminimized in the grinding of the ring. Also, the out of round bore issimilarly fit on the shaft of ultimate use. When the workpiece ring isrelatively thin, the expansion of the arbor sleeve may well expand thering, and in such event, any out of roundness of the bore may well beeliminated and the peripheral surface is ground in very substantialconcentricity therewith. Then, when the thin ring is relaxed, the groundsurface assumes the out of round condition of the relaxed bore. However,when the ring is later installed in a press fit on a shaft, its bore maywell again be expanded into roundness and the ground surface will againbe quite concentric.

The invention claimed is:

1. A machine for peripheral grinding of a ring-like workpiece includinga driven grinding wheel and a workhead which are relatively movable, theworkhead having a driven spindle and a driving disk secured to one endthereof; an arbor comprising a cylindrical flange and a coaxialforwardly projecting shank, means for exerting a driving connectionbetween the disk and flange when in surface contact but permittinglimited radial movement of the flange relative to the disk, a sleevemounted on said shank, said arbor defining a closed fluid system forexerting outward pressure on the sleeve, means for selectively varyingthe pressure respectively to expand the sleeve into non-slip engagementwith the bore of a workpiece to be ground and to release said workpiecefor replacement, and a pair of circumaxially spaced shoes engaging theperiphery of the arbor flange to support the arbor and workpiece on anaxis independent of the spindle with the workpiece in engagement withthe grinding wheel and while the spindle and disk rotate the arbor andworkpiece on said independent axis.

2. A machine for peripheral grinding of a ring-like workpiece includinga driven grinding wheel and a workhead which are relatively movable, theworkhead having a driven spindle and a magnetic chuck secured to one endthereof; an arbor comprising a cylindrical flange and a coaxialforwardly projecting shank, the flange being adapted for magnetic faceto face driving engagement with the chuck while being permitted limitedradial movement relative to the chuck, a sleeve mounted on said shank,said arbor defining a closed fluid system for exerting outward pressureon the sleeve, means for selectively varying the pressure respectivelyto expand the sleeve into non-slip engagement with the bore of aworkpiece to be ground and to release said workpiece for replacement,and a pair of circumaxially spaced shoes engaging the periphery of thearbor flange to support the arbor and workpiece on an axis independentof the spindle with the workpiece in engagement with the grinding wheeland while the spindle and chuck rotate the arbor and workpiece on saidindependent axis.

3. A grinding machine as set forth in claim 2 wherein said shoes arearranged to locate said independent axis at a position which islaterally offset toward the grinding Wheel from the spindle axis andwhich is also offset downwardly from the spindle axis.

4. A machine for peripheral grinding of a ring-like workpiece includinga driven grinding wheel and a workhead which are relatively movable, theworkhead having a driven spindle and -a magnetic chuck secured to oneend thereof; an arbor comprising a cylindrical flange and a forwardlyprojecting coaxial shank, a sleeve mounted on said shank and having acylindrical outer surface which is machined with reference to thecylindrical surface of the flange, said arbor flange being adapted formagnetic engagement by said chuck in face to face cont-act therewith butpermitting limited radial movement of the flange relative to the chuck,said arbor defining a closed fluid system for exerting outward pressureon the sleeve, means for selectively varying said pressure respectivelyto expand the sleeve into non-slip engagement with the bore of aworkpiece to be ground and to release said workpiece for replacement,and a pair of circumaxially spaced shoes engaging the periphery of thearbor flange to support the arbor and workpiece on an axis independentof the spindle with the workpiece in engagement with the grinding wheeland while the spindle and chuck rotate the arbor and workpiece on saidindependent axis.

5. A machine for peripheral grinding of a ring-like workpiece includinga driven grinding wheel and a workhead which are relatively movable, theworkhead having a driven spindle coaxially supporting an annularmagnetic chuck; an arbor comprising oppositely projecting coaxial shanksand an interposed cylindrical flange and having one shank extending intothe central opening of the chuck for limited radial movement thereinwith the flange engaging and moving along the end face of the chuck andwith the other shank projecting forwardly into the plane of the grindingwheel adjacent the periphery thereof, a cylindrical sleeve mounted onsaid forwardly projecting shank, said arbor defining a closed fluidsystem for exerting outward pressure on the sleeve, means forselectively varying said pressure respectively to expand the sleeve intononslip engagement with the bore of a workpiece to be ground and torelease said workpiece for replacement, and a pair of circumaxiallyspaced shoes engaging the periphery of the arbor flange to support thearbor and workpiece on an axis independent of the spindle with theworkpiece in engagement with the grindnig wheel and while the spindleand magnetic chuck rotate the arbor and workpiece on said independentaxis.

6. A grinding machine as set forth in claim 5 wherein the said shoes arerespectively located on opposite sides of the vertical plane whichincludes the spindle axis.

7. A grinding machine as set forth in claim 6 wherein the said sleeve isprovided with a cylindrical peripheral surface which is machined withreference to the periphery of said arbor flange.

8. A machine for peripheral grinding of a ring-like workpiece includinga driven grinding wheel and a workhead which are relatively movable, theworkhead having a driven hollow spindle coaxially supporting an annularmagnetic chuck; an arbor comprising oppositely projecting coaxial shanksand an interposed coaxial cylindrical flange and having one shankextending into the central bore of the chuck for limited radial movementtherein with the flange engaging and moving along the face of the chuckand with the other shank projecting forwardly into the plane of thegrinding wheel adjacent the periphery thereof, a cylindrical sleevemounted on said other shank, said arbor having axial and radial passagescontaining hydraulic fluid under pressure which expands said sleeve intonon-slip engagement with the bore of a workpiece to be ground, a plugretractable rearwardly in said axial passage to reduce said pressure andthereby to relax said sleeve for the replacement of said workpiece,means extending through said spindle for selectively retracting saidplug, and a pair of circumaxially spaced shoes engaging the periphery ofthe arbor flange to support the arbor and workpiece on an axisindependent of the spindle with the workpiece in engagement with thegrinding wheel and while the spindle and magnetic chuck rotate the arborand workpiece on said independent axis.

9. A machine for peripheral grinding of a ring-like workpiece includinga driven grinding wheel and a workhead which are relatively movable, theworkhead having a driven hollow spindle coaxially supporting an annularmagnetic chuck; an arbor comprising oppositely projecting coaxial shanksand an interposed coaxial cylindrical flange and having one shankextending into the central bore of the chuck for limited radial movementwith the flange engaging and movable along the face of the chuck andwith the other shank projecting forwardly into the plane of the grindingwheel adjacent the periphery thereof, a sleeve mounted on said othershank, said arbor defining a closed system for maintaining hydraulicfluid under pressure which system includes an axial passage in eachshank and radial passages in said other shank, a plug biased forwardlyto a closed position in the axial passage of said one shank, anadjustable plug in said other shank to set a pressure in said systemcapable of expanding said sleeve into non-slip engagement with the boreof a workpiece to be ground, a fluid motor mounted on the rear of saidspindle having means extending therethrough and connected with saidbiased plug to retract the same and reduce pressure in said systemwhereby to relax the sleeve for replacement of said workpiece, and apair of circumaxially spaced shoes engaging the periphery of the arborflange to support the arbor and workpiece on an axis independent of thespindle and with the workpiece in engagement with the grinding wheel andwhile the spindle and chuck rotate the arbor and workpiece on saidindependent axis.

10. A grinding machine for a ring-like workpiece as set forth in claim 9wherein said shoes are respectively spaced on opposite sides of avertical plane including the axis of the spindle and are also arrangedto locate said independent axis at a position laterally displaced fromthe spindle axis toward the grinding wheel and displaced downwardly fromthe spindle axis.

11. A grinding machine for a ring-like workpiece as set forth in claim10 wherein said sleeve is provided with a cylindrical periphery which ismachined with reference to the periphery of said arbor flange.

References Cited by the Examiner UNITED STATES PATENTS 3,080,686 3/196-3Healy et a1. 51103 3,093,938 6/1963 Balsiger 51103 3,176,439 4/1965Gabriel et a1. 51-237 LESTER M. SWINGLE, Primary Examiner.

1. A MACHINE FOR PERIPHERAL GRINDING OF A RING-LIKE WORKPIECE INCLUDINGA DRIVEN GRINDING WHEEL AND A WORKHEAD WHICH ARE RELATIVELY MOVABLE, THEWORKHEAD HAVING A DRIVEN SPINDLE AND A DRIVING DISK SECURED TO ONE ENDTHEREOF; AN ARBOR COMPRISING A CYLINDRICAL FLANGE AND A COAXIALFORWARDLY PROJECTING SHANK, MEANS FOR EXERTING A DRIVING CONNECTIONBETWEEN THE DISK AND FLANGE WHEN IN SURFACE CONTACT BUT PERMITTINGLIMITED RADIAL MOVEMENT OF THE FLANGE RELATIVE TO THE DISK, A SLEEVEMOUNTED ON SAID SHANK, SAID ARBOR DEFINING A CLOSED FLUID SYSTEM FOREXERTING OUTWARD PRESSURE ON THE SLEEVE, MEANS FOR SELECTIVELY VARYINGTHE PRESSURE RESPECTIVELY TO EXPAND THE SLEEVE INTO NON-SLIP ENGAGEMENTWITH THE BORE OF A WORKPIECE TO BE GROUND AND TO RELEASE SAID WORKPIECEFOR REPLACEMENT, AND A PAIR OF CIRCUMAXIALLY SPACED SHOES ENGAGING THEPERIPHERY OF THE ARBOR FLANGE TO SUPPORT THE ARBOR AND WORKPIECE ON ANAXIS INDEPENDENT OF THE SPINDLE WITH THE WORKPIECE IN ENGAGEMENT WITHTHE GRINDING WHEEL AND WHILE THE SPINDLE AND DISK ROTATE THE ARBOR ANDWORKPIECE ON SAID INDEPENDENT AXIS.